A number of different processes use laser light for manufacturing components. Manufacturing processes using laser beams includes selective laser sintering (SLS) and selective laser melting (SLM) apparatus and also methods of building components by curing of polymers such as laser lithography, for example stereolithography (SLA). Such processes can be generically described by such terms as additive manufacturing, rapid manufacturing or rapid prototyping.
In a typical SLS or SLM process, a thin layer of powder is deposited over a build area or powder bed within a SLS or SLM apparatus. A focused laser beam is scanned across portions of the powder layer that correspond to a cross-section of the three-dimensional article being constructed such that the powder at the points where the laser scans is consolidated either by sintering or by fusion. The cross-section is typically generated from a 3-D description of the component generated by scanning an original component or from computer-aided design (CAD) data.
After consolidation of a layer, the build surface is lowered by the thickness of the newly consolidated layer and a further layer of powder is spread over the surface. Again, the surface is irradiated with a laser beam in portions of the layer that correspond to a cross-section of the three-dimensional article, the newly consolidated layer being joined to the initial consolidated layer. This process is repeated until the component is completed.
In order to manufacture components according to, for example, an SLS or SLM process, a laser beam must be supplied to a work surface within the apparatus and controlled with a high degree of accuracy. The optics allowing control of the laser beam for manufacturing purposes include focusing optics, scanners and other lenses, and are extremely sensitive. Typically, the sensitive optics are built into the chassis of the manufacturing apparatus and must be set up on site by a skilled technician. Furthermore, service and repair of the optics requires downtime of the machine and can be difficult to achieve on-site, which is typically a dusty environment and non-conducive to optical repairs.